Even though interstitial cystitis is not associated with ongoing bacterial infections, previous infections may predispose or account for this inflammatory condition of the bladder. Understanding the molecular basis of bladder infections caused by E. coli will provide important insight into the possible sequelae of these infections such as interstitial cystis and unveil novel therapeutic and preventative strategies. This proposal represents an intensive effort combining high powered genetics, biochemistry, crystallography, and high resolution electron microscopy with a relevant primate model of cystitis to identify the molecular basis of the factors that are critical in bacterial cystitis. The exact roles played by bacterial adhesive organelles, including P pili, type 1 pili and curli, in causing bladder disorders, will be studied by testing a panel of isogenic mutant derivatives of the uropathogenic strain DS17 to i) bind to human and monkey bladder tissue in situ and ii) cause cystitis in cynomolgus monkeys. Receptor analogues will be used as inhibitors to determine the molecular basis of the adhesin-receptor interaction. Human bladder tissue obtained from patients with either bacterial cystitis or interstitial cystitis and tissue from infected monkeys will also be subjected to special staining using anti-type 1, anti-FimH, and anti-P, anti-PapG and anti-curli antisera to elucidate whether these adhesions are expressed in vivo by adherent microorganisms or possibly deposited on the bladder mucosa. The presence of these factors in interstitial cystitis tissue, or cross-reacting antigens, would suggest that bacterial infections may be a predisposing factor. Purified PapG and FimH adhesions will also be tested for their ability to confer protection against cystitis in the primate model. In order to definitively analyze the interactive surface of the adhesin molecule as it is presented to the host, the first three dimensional structure of a bacterial adhesin (FimH) will be determined. A thorough understanding of the structural basis of microbial attachment, its role in virulence, and the interactive surfaces of an adhesin that facilitate its interaction with host receptors will give us a broad understanding of this disease that primarily affects women and unveil strategies that can be developed to block the host-pathogen interaction and reveal relevant vaccine candidates that protect against infection.